Capacitive sensor arrangements are used in various areas of a motor vehicle. One example is the detection of an operating event, in particular approach of a person to the motor vehicle, which, depending on the design, may initiate an authentication dialog. Another example is the detection of an imminent collision between a person and a moving component, for example a tailgate, of the motor vehicle.
The method in question relates to the operation of a capacitive sensor arrangement of a motor vehicle which is used to determine distance values to a measurement object. For this purpose, the sensor arrangement is assigned a control unit for controlling it. The sensor arrangement has two electrodes each assigned a connection arrangement for connection to the control unit. The fault-free connection between the electrodes and the control unit is of very special importance in order to avoid distance values being incorrectly determined on account of high contact resistances, for example.
In the known method for operating a capacitive sensor arrangement of a motor vehicle (DE 10 2013 112 418 A1), on which the present invention is based, a diagnostic routine is provided in order to check the electrical connection state of the electrode with respect to the electrical connection to the control unit. In this case, the check of the electrical connection state quite generally traces back to a check of the electrical resistance of diagnostic paths inside the sensor arrangement. Although the known method makes it possible to reliably detect fault states, the known method always requires that the electrodes each make contact with two connecting lines in order to be able to check the relevant resistance.